ref_configuration.md

◀︎ Airlift • ◀︎ Reference

Reference: Configuration

Configuration Object and @Config

Define classes using the @Config annotation. The value of the annotation is the name of a config value. At runtime, Airlift uses the value from the command line or a properties file (in that order) as the argument to the annotated method. If no command line or property is present with the name, the setter is never called and will retain its default value.

Example:

public class MyConfig
{
    private String address;
    
    @Config("foo.bar.address")
    public MyConfig setAddress(String address)
    {
        this.address = address;
        return this;
    }
}

Configuration Values

Source configuration can be specified on the command line or via property files. Airlift will map these configuration values to an annotated and bound Java model class.

Configuration files are standard field=value property files. Airlift uses the file defined by system property config (i.e. pass on the command line -Dconfig=path-to-config-properties-file).

Configuration Binding

The main way to bind configuration objects is via the ConfigBinder utility:

ConfigBinder.bindConfig(binder).bindConfig(MyConfigObject.class);

You can also do conditional binding. See the note here for details.

@ConfigSecuritySensitive

Airlift logs configuration values. However, some values may be too sensitive to log. Annotate the with @ConfigSecuritySensitive to avoid logging.

ConfigDefaults

The value of a config field in your configuration object will be the default value if one isn't found in property files, etc. You can also set the default values via the ConfigDefaults binding mechanism:

configBinder(binder).bindConfigDefaults(MyConfig.class, config -> config.setSomeValue("foo"));

@DefunctConfig

You may have the need to permanently prevent a config name being used (it may have lost its meaning, etc.). Add @DefunctConfig("name") to your Config class and if a @Config is found with the same name Airlift will throw an exception.

@LegacyConfig

If you want to migrate from an old config value to a new one use @LegacyConfig. A diagnostic will be logged informing that the config is being renamed. You can optionally specify what the replacement is.